Desenvolvimento de nanocápsulas poliméricas contendo extrato de mentha x villosa huds para aplicação fotoprotetora

Abstract

Exposure to solar radiation, although essential for vitamin D synthesis and the maintenance of homeostasis, can cause serious health damage when excessive. Burns, hyperpigmentation, oxidative stress, deoxyribonucleic acid (DNA) mutations, and immunosuppression are among the main harmful effects, increasing the risk of skin cancer and premature aging. In this context, the use of effective and safe photoprotective agents becomes essential, and natural products, when associated with nanotechnological systems, stand out due to enhanced efficacy, antioxidant activity, and reduced environmental impact. This study aimed to develop polymeric nanocapsules containing Mentha x villosa Huds extract with potential photoprotective application. Both the crude ethanolic extract (CEE) and the dechlorophyllated extract were obtained, followed by quantification of phenolic compounds using the Folin-Ciocalteu method and of rosmarinic acid (RA) by high-performance liquid chromatography (HPLC). Antioxidant activity was evaluated using DPPH and ABTS radical scavenging assays. A preformulation study was then conducted using different types of nanosystems (double emulsion nanocapsules, liposomes, and nanostructured lipid carriers), with polymeric nanocapsules containing CEE being selected due to better solubility and particle size. Based on this, a Box-Behnken experimental

design was applied using Tween®80 (50–100 mg), extract (1–9 mg), and PCL- 10 (30–70 mg) as independent variables. The formulations were characterized in

terms of hydrodynamic diameter, polydispersity index (PdI), zeta potential, morphology, Fourier-transform infrared spectroscopy (FTIR), thermal analyses (thermogravimetric analysis and differential scanning calorimetry), RA content and encapsulation efficiency, sun protection factor (SPF), physicochemical stability, in vitro release profile, and cellular toxicity in HaCaT cell line. The extracts showed a high concentration of rosmarinic acid (76.24 mg/g for CEE and 68.86 mg/g for the dechlorophyllated extract) and phenolic compounds (263.44 ± 0.50 mg GAE/g in CEE and 324.23 ± 0.22 mg GAE/g in the dechlorophyllated extract). Formulation F18 (50 mg of Tween®80, 5 mg of extract, and 70 mg of PCL-10) demonstrated better stability during 90-day storage, particularly under refrigeration at 4°C, as well as a sustained release profile over 24 h, with greater RA release compared to F17 (50 mg of Tween®80, 3 mg of extract, and 70 mg of PCL-10). Regarding SPF, formulations F17 and F18 showed values of 15.31 and 10.22, respectively, while the isolated extract reached only 1.06, highlighting the significant enhancement of photoprotective activity after encapsulation. Both formulations exhibited a concentration-dependent toxicity profile, maintaining over 85% cell viability at concentrations ranging from 6.25 to 25 μg/mL of the nanoformulations. Moreover, the extract showed a cytoprotective effect, which may be related to the high RA content. Thus, the results demonstrate that nanoencapsulation of M. x villosa Huds extract in polymeric nanocapsules is a promising strategy for developing natural, effective, safe and environmentally sustainable sunscreens.